140 Annals of the South African Museum. 
pod not so well marked, 5th not quite equal to 3rd plus 4th and pro- 
portionately stouter, with more robust spines. 
Length : 8-10 mm. 
Colour : In spirit, uniform pinkish. 
Locality: Beacon E. of East London N. 4 E., distant 10 miles. 
52 fathoms. 3 ¢ ¢,1 ovigerous ?; Umhloti River mouth NW.? W., 
distant 15 miles (Natal). 100 fathoms. 1 (immature) ¢@. s.s. “ Pieter 
Faure.” 12/7/01 and 19/12/00. (S.A.M. Nos. A2750 and A2751.) 
Geogr. Distribution : Arctic Ocean, North Atlantic, Norway (Kroyer, 
Sars, ete.); California, 46-57 fathoms (Pearse). Sars regards its 
occurrence in the Mediterranean (Heller, Costa) as very doubtful. 
TRIODOS n. g. 
Head with postero-antennal corners distinct, though not prominent. 
One pair of eyes. Side-plate 4 obliquely truncate below posterior 
angle (as in Ampelisca). Pleon with tufts of setae as in Haploops. 
Mandibular palp with 3rd joint elongate. Peraeopods 3 and 4 with 
2nd joint very wide, anterior margin evenly curved, 5th joint without 
transverse rows of spines, 7th joint as in Ampelisca. Peraeopod 5 
with 2nd joint distally expanded, the plumose setae extending round 
posterior angle but not reaching junction with 8rd, 3rd not shorter 
than 4th, 5th equal to 8rd and 4th together, 6th narrow, 7th spini- 
form. Third uropod with rami foliaceous, extending beyond Ist and 
2nd uropods. Telson of moderate size, deeply cleft. 
This genus combines in a remarkable manner the characters of the 
three hitherto recognised genera of Ampeliscidae, whence the name, 
signifying a “meeting of three ways.” 
TRIODOS INSIGNIS Nl. Sp. 
(Plate XXVI. Figs. 8-10.) 
Head projecting slightly over base of Ist antenna, 1 pair of very 
small corneal lenses in upper angles of head. Side-plate 1 strongly 
convex below, not concealing base of 2nd antenna, inferior margin of 
side-plates 2-4 not very convex. Pleon somewhat compressed, seg- 
ment 4 with a triangular keel on its posterior half bearing a tuft of 
setae behind, segment 5 with a tall upstanding keel on its posterior 
half also bearing a tuft of setae behind, postero-inferior angle of 3rd 
seoment rounded. 
Telson a little longer than broad, ovate, cleft nearly to base, apex 
with 2 setae. 
